Ethylenimine (EI) is an active three-membered cyclic amine and is a very useful compound since it can introduce an amino group by an addition reaction, substitution reaction, ring opening reaction and the like. EI is a commercial chemical used as raw material in pharmaceutical and amino resins. EI can also be used to determine the desired product mix of alkylene amines (ethylenediamine, diethylenetriamine and triethylenetetramine, etc.) when reacting with ammonia. The current alkylene amines process based on ethylene dichloride and ammonia gives no product flexibility.
EI has been formed by catalytic dehydration of monoethanolamine (MEA) in a vapor phase over a catalyst. Examples of such processes are disclosed and taught in U.S. Pat. Nos. 4,289,656, 4,301,036, and 4,337,175.
Hideaki Tsuneki, “Acid-base catalysis: on the example of ethylenimine production,” Applied Catalysis A: General, 2001, 221, 209-217 discusses certain solid acid-base catalysts showing high catalytic activity and selectivity in vapor phase intramolecular dehydration of MEA to EI.
Operating a vapor phase has problems because catalytic performance (selectivity and life of the catalyst) can be issues and also processes need to be performed at high process temperatures.
EI has also been produced from MEA in the liquid phase by using H2SO4 and NaOH (Wenker reaction). However, this reaction forming large quantify of waste water containing by-product Na2SO4 in the process, which can be a problem.
Accordingly, there is a need for an improved low temperature liquid phase catalytic process for the dehydration of MEA to EI and water.